Outside linebacker Jason Worilds is expected to make his fifth start of the season tonight when the Steelers visit the San Francisco 49ers.

The difference is that, unlike in his previous four starts, Worilds will play for James Harrison instead of LaMarr Woodley.

Woodley, hampered by a hamstring injury since the end of October, is expected to start at left outside linebacker. Worilds switches to the right side while Harrison serves a one-game suspension.

The move from the left to the right side isn't expected to be too much of an adjustment for Worilds since he practices at both outside linebacker spots.

"I think I would have to drop a little more (into pass coverage) from the right side," said Worilds, who has three sacks in the Steelers' past three games. "I guess it varies each week, but I do believe there is more coverage responsibilities on the right side."

It's official: Playoffs await Steelers

The Steelers clinched a playoff berth Sunday without ever taking the field.

When the Tennessee Titans were upset by the previously winless Indianapolis Colts, the idle Steelers (10-3) officially earned at least a wild-card berth in the AFC. The division rival Baltimore Ravens also clinched at least a wild-card berth yesterday when Oakland lost to Detroit.

The New England Patriots (11-3) clinched the AFC East title with a win over Denver. The Houston Texans (10-4) had clinched the AFC South title a week earlier.

That leaves two AFC berths remaining.

More for Gore

Something has to give when Frank Gore goes against the Steelers' run defense.

Gore became the first player in 49ers history to rush for 100 or more yards in five consecutive games this season. Since the beginning of October, Gore has rushed for 906 yards and five touchdowns while averaging 5.2 yards per carry.

The Steelers haven't allowed a 100-yard rusher since Houston's Arian Foster gashed them for 155 yards on Oct. 2.

"I've always had a high opinion of Frank Gore and what he contributes to anybody's offense," Steelers defensive coordinator Dick LeBeau said. "He's really your prototype of an NFL back who can carry 40 times a game if you want him to. They probably would leave him out there all the time if they could, but he has to get some rest some time."

HOW THEY STACK UP

49ers running back Frank Gore vs. Steelers defense

49ERS RB GORE: The 49ers are a difficult team to stop when Gore runs effectively. San Francisco's workhorse has rushed for 1,054 yards on 234 carries. For all of the talk about first-year coach Jim Harbaugh and quarterback Alex Smith, the 49ers struggle when Gore fails to get on track. Gore has 345 total yards from scrimmage in San Francisco's past two Monday Night Football appearances, but he was held in check in losses to Baltimore and Arizona.

STEELERS DEFENSE: The Steelers want to discourage quarterback Alex Smith from leaning on tight end Vernon Davis and wide receiver Michael Crabtree. But inside linebackers James Farrior and Lawrence Timmons figure the key to stopping the 49ers' offense is to frustrate Gore. Like San Francisco, the Steelers are solid against the run. Defensive end Brett Keisel and nose tackle Casey Hampton have been nearly unstoppable the past few weeks.

ADVANTAGE: STEELERS

Gore gets many of his yards off tackle, and the 49ers will try to attack outside linebacker Jason Worilds, who starts in place of suspended James Harrison. Worilds, however, is a proven pass rusher with three sacks this season. He should get enough help from the other linebackers, particularly Farrior and Timmons, to help ensure the Steelers keep Gore in check.

Worilds has the potential to be even better coming off the right side. He played right DE in college and it will probably feel more natural for him coming from that side. Hope Woodley is truly ready and doesn't tweak that hammy anymore than it already is. Would have been interesting to see if they started him if Harrison played this week.